Various catalyst systems have been employed to produce high trans-1,4-polybutadienes. Certain catalyst systems have been used to produce high trans-1,4-polybutadiene having two distinct melting points. U.S. Pat. No. 5,174,838, to Sandstrom et al, discloses a cobalt based catalyst to produce a trans 1,4-polybutadiene rubber having 75% to 85% trans 1,4-content, 12% to 18% 1,2-content, 3 to about 8% cis 1,4-content and, in its uncured state, having a major melting point in a range of about 35.degree. C. to about 45.degree. C. and a second minor melting point in the range of about 55.degree. C. to about 65.degree. C. U.S. Pat. No. 5,037,912, to Patterson et al, discloses an organolithium and alkali metal alkoxide catalyst in a process for synthesizing trans 1,4-polybutadiene having a trans isomer content of about 80% to about 90% and two distinct melting points, namely a first melting point of about 60.degree. C. to about 80.degree. C. and a second melting point of about 135.degree. C. to about 155.degree. C.
U.S. Pat. No. 4,619,982 to Jenkins displays the use of a compound of a rare earth element and an organomagnesium compound to produce high trans polydiene polymers.
The use of trans 1,4-polybutadiene has been shown for various purposes including tire tread rubber compounds and increasing the green strength of rubber mixtures as disclosed in U.S. Pat. Nos. 5,174,838, 4,510,291 and Japanese Patent Application Publication No. Hei 3-65825.
High trans 1,4-polybutadiene is generally considered to be a thermoplastic resin rather than a rubber in its uncured state at room temperature due to its high crystallinity. Due to the numerous double bonds in its backbone high trans 1,4-polybutadiene is readily blended and co-cured with elastomers such as natural rubber and high cis-polybutadiene.